In well installations of the kind where an ascending pipe through which the water in the well rises, is arranged to be connected via a pipe coupling to a pipe, deposited in the ground below freezing level and leading to a pump, it is common practice to provide a knee pipe joint at the lower end, inside some cement rings stacked on top of one another in the ground and having an inner diameter of sufficient size to allow a person to descend into the rings to effect interconnection of the pipes and conduits. As cement rings of this kind are heavy to transport and position on top of the well, which may be a drilled deep-well, and in addition they are rather bulky, particularly as the lid covering the uppermost cement ring always will be visible, attempts have been made to find new ways of eliminating these disadvantages.
In accordance with one suggested solution a steel well casing is used, which casing is inserted down into the well opening and is of such a length that the upper casing end reaches up to ground level. At a frost-free level, the well casing is provided with a lateral pipe socket or connecting branch to which is connected a pipe leading to the pump. A slide means is vertically displaceable inside the well casing and the ascending pipe is connected to the lower end of said slide means. The slide is displaceable in a guide provided on the inner face of the well casing, this displacing movement effected by means of a nut screwed on a vertically extending rod on the slide means. The rod extends all the way up to the upper end of the well casing, penetrating an end plate positioned at this end and above which the adjusting nut is provided. A disadvantage experienced with a coupling arrangement of this type is its tendency to become stuck whereby, when the ascending pipe and a valve or pump provided at the lower end thereof are to be pull up from the well opening for inspection and overhaul, it may be separated from the guide only with great difficulty. Because of the comparatively long and heavy steel well casing, the coupling device is difficult to handle and transport and the manufacturing costs are high.